Egestion

Introduction

The small intestine absorbs the majority of the water in the gut contents. Most of the digested food is absorbed by the time these contents reach the end of the small intestine. Water makes up the rest of this substance. Some of these other substances are:

• Microorganisms (both living and dead)
• Cells from the gut lining
• Compounds that are indigestible, such as cellulose from plant cell walls

The first section of the big intestine is known as the colon. It absorbs the majority of the remaining liquid. This results in faeces, a semi-solid waste product. The rectum, the last section of the large intestine, is where the faeces are kept. When these faeces flow out of the body through the anus, it is called egestion.

The process of nutrition involves various steps such as Ingestion, digestion, absorption, assimilation and egestion.

• The process of an animal ingesting food or “eating food” is known as ingestion. We ingest food when we put it in our mouths with our hands.
• The process by which large, insoluble molecules in food are broken down into small and simpler molecules that the body can absorb easily is called digestion.
• The process through which digested food travels through the intestinal wall and into the bloodstream is known as absorption.
• The process through which ingested food is taken in by the body cells and then used for providing energy, growth and repair of the cells is known as assimilation. The blood transports the digested and absorbed food to every region of the body.
• The process of egestion is the removal of undigested food from the body. Our bodies do not digest the food that we eat entirely. A portion of it remains undigested and cannot be utilised by the body. As a result, it is expelled from the body in the form of faeces when we go to the toilet. This is the meaning of egestion in biology.
• The process of excreting unusable or undigested material from a cell, as in single-celled organisms or from the digestive system of multicellular animals, is referred to as egestion.

The fact that flexible food sacs or vacuoles are formed around any eaten food in an amoeba is remarkable. The digestive enzymes are subsequently released inside these sacs, causing the food particles to be slowly digested. They reach the protoplasm’s extreme periphery when the digestion is almost complete.

These sacs eventually fuse with the cell membrane, resulting in the formation of a channel. The sac then progressively absorbs the cell membrane and expels the contents. This is the best way of understanding the process of egestion.

Egestion occurs in complex species as well. The meanings of the terms “excretion” and “egestion” are so similar that they can be interchanged in different situations. It is also known as elimination. 

The peristaltic movement in mammals’ large intestine aids in the removal of undigested food from their bodies. 

Egestion in Animals

Egestion in smaller animals

Let us consider amoeba as an example. Amoeba has no specific location for eliminating undigested food. When a large amount of undigested food accumulates inside an amoeba, the cell membrane ruptures at any point and the unabsorbed food is flung out of the amoeba’s body.

Food vacuoles in unicellular organisms eventually merge with the cell membrane and burst, discharging undigested wastes to the outside.

Egestion in complex animals (like humans)

The process of egestion in humans and other higher animals involves waves of muscular contractions of the colonic walls, which move the faeces towards the rectum. The rectum ampulla is used to temporarily store faeces.

In egestion, the rectal walls stretch when faecal waste accumulates. The stretch sensors in the rectal walls are triggered, the rectal muscles contract reflexively, the internal anal sphincter relaxes and the skeletal muscle of the external anal sphincter contracts. 

As a result, there is a strong need to eliminate the faeces. When not acted upon, reverse peristaltic waves occur, in which the material returns to the colon for further water absorption and temporary storage until the next wave of transversal and descending colon muscle activity.

Valsalva manoeuvre is performed during defecation. That is, air is forced out through a blocked airway. As the diaphragm in the chest is pushed down, the lungs stop breathing. This puts strain on the digestive system.

Egestion in Human Beings

For humans, egestion is the ejection of waste food elements from the body, especially undigested materials from the gut through the anus. Excretion, in which waste materials that are the result of the body’s metabolism are removed, should not be mistaken with egestion.

All the digested food products, as well as the minerals and vitamins that the body needs, should be eliminated from the runny components by the time it reaches the end of the small intestine. 

The undigested components of food, such as cellulose, from the ingestion of plant-based foods are left. The contents of the small intestine are subsequently moved on to the big intestine.

Process of Egestion in Human Beings

In unicellular organisms, unprocessed food is transported to the cell membrane and expelled outside the body by egestion. Not all eukaryotic animals have a digestive system. The hydra’s gut sac processes the meal and the undigested material is thrown out through the mouth.

The higher animals’ digestive systems are highly evolved and adaptable. Food that has not yet been metabolised moves to the large intestine after being digested and absorbed into the body.

In the large intestine, the excess moisture, electrolytes and several vitamins are absorbed. The large Intestine has no digestive function. Many bacteria can be found in it, trying to break down some undigested compounds that result in the production of certain vitamins.

Since a portion of the meal that humans eat goes uneaten and undigested, it must be removed from the body. This is what happens in egestion in human beings. Unprocessed food residues accumulate in the colon. It is regularly evacuated from the body through the colon and the anus (or the cloaca). Peristaltic waves push the components to the anus. Since the animal body uses the majority of the water, the ejected non-utilised food particles are semisolid or thick. This is how egestion in human beings takes place.

Conclusion

Egestion is the process of eliminating undigested waste products and food from an organism’s body. The expelled materials are undigested food and other hazardous things that remain after digestion. Egestion is done mainly through the anus or the mouth ( for example Jellyfish, use their mouths to eat and expel waste.) 

Egestion also aids in the removal of any possibly dangerous or toxic component that has entered our bodies via the oral route. It also aids the body’s removal of excess heme by producing side products that are excreted or recycled in the faeces or urine.

Egestion in human beings is an important activity because it allows undigested food to exit the system. If the bowel movement is prolonged for an extended period of time, it can lead to a megacolon and bowel rupture.